Conducting polymers have been the subject of intense research activity for the past decade. Currently, much work is devoted to the synthesis of conducting polymers for use in a variety of applications. Polyacetylene, the prototype conducting polymer, has been successfully demonstrated to be useful in constructing p-n heterojunctions, Schottky barrier diodes, liquid junction photoelectrochemical solar cells, and, more recently, as the active electrode in polymeric batteries.
The improved electrochemical synthesis of polypyrrole has led to its use as coating for the protection of n-type semiconductors against photocorrosion in photoelectrochemical cells. Research studies have shown that pyrrole is not the only five-membered heterocyclic aromatic ring compound to undergo simultaneous oxidation and polymerization. Thiophene also undergoes electrochemical polymerization and oxidation to yield an oxidized conducting polymer. Conducting polyheterocycles, such as polypyrrole and polythiophene, have demonstrated dramatic improvement in oxidative stability over other conducting polymers. However, polyheterocycles, like other known conducting polymers, are hampered by inferior mechanical properties.
Polythiophene is very difficult to synthesize as free standing films. Films of polythiophene can be synthesized by electrochemical techniques on the surface of an electrode . Heretofore the mechanical integrity of polythiophene films has been so poor that it is extremely difficult to remove the film from the electrode surface without fragmentation of the film.